1. Field of the Invention
The invention relates to a phase insulation paper and an electric motor provided with the phase insulation paper. More particularly, this invention relates to a phase insulation paper that phase insulates coil ends of phase stator coils, and an electric motor which is phase insulated by that phase insulation paper.
2. Description of the Related Art
A stator in an electric motor typically has a stator core with a plurality of teeth on the inside surface, and coils wound around the teeth while forming coil ends at both end faces of the stator core. When the electric motor is a multiple phase alternating current motor, different phase coils must be phase insulated at the end face of the stator core where the coil ends of the phase coils come together.
As described in JP(A) 63-314151, phase insulation of the coil ends corresponding to the phase coils is typically performed by inserting a sheet of phase insulation paper between adjacent coil ends.
Electric motors and the like used in vehicles must be small. In order to make these electric motors more compact, the coil ends are press-formed to the stator core end face after the phase coils and phase insulation paper have been attached to the stator. During this press-forming, the coils deform greatly, particularly at a portion where they rise from slots (between adjacent teeth), such that the phase insulation paper greatly deforms three dimensionally.
The phase insulation paper disclosed in JP(A) SHO 63-314151 above does not take this large deformation that occurs during press-forming of the coil ends into consideration. As a result, when the coil ends are press-formed in order to make the electric motor more compact, the phase insulation paper becomes offset or damaged, which may result in poor phase insulation.